Predictive performance of passive leg raising in patients with atrial fibrillation: Reply

Abstract

Editor—We thank Dr Mallat for his valuable comments regarding our manuscript.1Kim N Shim JK Choi HG Kim MK Kim JY Kwak YL Comparison of positive end-expiratory pressure-induced increase in central venous pressure and passive leg raising to predict fluid responsiveness in patients with atrial fibrillation.Br J Anaesth. 2016; 116: 350-356Abstract Full Text Full Text PDF PubMed Scopus (18) Google Scholar We also acknowledge the possibility that the PEEP-induced reduction in venous return and, consequently, cardiac output may indeed be attributable to the increase in venous resistance and not to the increase in central venous pressure (CVP) as the pressure gradient for the venous return is maintained.2Peters J Mack GW Lister G The importance of the peripheral circulation in critical illnesses.Intensive Care Med. 2001; 27: 1446-1458Crossref PubMed Scopus (57) Google Scholar It is reasonable, therefore, to assume that the PEEP-induced increase in CVP may not be a suitable predictor of fluid responsiveness from the physiological point of view, as was implied by Dr Mallat. Nonetheless, high levels of PEEP are almost invariably associated with an increase in CVP and decrease in cardiac output.3Magder S Lagonidis D Erice F The use of respiratory variations in right atrial pressure to predict the cardiac output response to PEEP.J Crit Care. 2001; 16: 108-114Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar Unfortunately, it is not possible to obtain accurate measurements regarding the complex mechanical interaction among the lung, pericardium, and heart in our clinical practice, let alone the transmural pressure of the affected chambers. Likewise, the increase in venous resistance has only been speculated as the cause of the PEEP-induced reduction in the venous return and has not been measured.4Fessler HE Brower RG Wise RA Permutt S Effects of positive end-expiratory pressure on the gradient for venous return.Am Rev Respir Dis. 1991; 143: 19-24Crossref PubMed Scopus (115) Google Scholar Considering that there was no tendency towards collapse of the inferior and superior vena cava as a result of lung expansion,5Jellinek H Krenn H Oczenski W Veit F Schwarz S Fitzgerald RD Influence of positive airway pressure on the pressure gradient for venous return in humans.J Appl Physiol. 2000; 88: 926-932PubMed Google Scholar it is also unclear whether there exists a relationship between the PEEP-induced changes in CVP and the increase in venous resistance. Despite many inherent flaws, based on a simple Guytonian model, Geerts and colleagues6Geerts BF Aarts LP Groeneveld AB Jansen JR Predicting cardiac output responses to passive leg raising by a PEEP-induced increase in central venous pressure, in cardiac surgery patients.Br J Anaesth. 2011; 107: 150-156Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar have shown solid results regarding the role of the PEEP-induced increase in CVP as a predictor of fluid responsiveness in cardiac surgical patients. Based on their work, we performed our study in patients with chronic atrial fibrillation, in whom the most practical arterial waveform- derived dynamic preload indices from the heart–lung interaction cannot be applied.7Lansdorp B Lemson J van Putten MJ de Keijzer A van der Hoeven JG Pickkers P Dynamic indices do not predict volume responsiveness in routine clinical practice.Br J Anaesth. 2012; 108: 395-401Abstract Full Text Full Text PDF PubMed Scopus (107) Google Scholar As our results indicate, we can only imply that the PEEP-induced increase in CVP was not able to predict fluid responsiveness in patients with atrial fibrillation following valvular heart surgery. It would be beyond the scope our study to imply that this concept previously proved by Geerts and colleagues6Geerts BF Aarts LP Groeneveld AB Jansen JR Predicting cardiac output responses to passive leg raising by a PEEP-induced increase in central venous pressure, in cardiac surgery patients.Br J Anaesth. 2011; 107: 150-156Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar would be misleading. Yet, we think that the comments provided by Dr Mallat and colleagues are indeed valuable and should be considered when planning further studies in that regard. None declared. Predictive performance of passive leg raising in patients with atrial fibrillationBritish Journal of AnaesthesiaVol. 117Issue 3PreviewEditor—We read with interest the study by Kim and colleagues1 reporting performance of the stroke volume (SV) change during passive leg raising (PLR) for predicting fluid responsiveness in patients with atrial fibrillation. The cardiac rhythm is expected to have very little impact on the performance of PLR-induced change in SV, so why did Kim and colleagues1 find an area under the ROC curve (AUC) of only 0.77, markedly lower than AUCs >0.95 as reported in patients with regular cardiac rhythm?2 3 Full-Text PDF Open Archive